Telomere dysfunction is a well-documented contributing factor to diseases such as cancer. Our proposed work should identify new targets and pathways and provide mechanistic details of their function, thereby facilitating in our identifying novel targets for therapies, gaining new insight into the pathways and signals for disease initiation, and shedding light on new and more effective treatment options. We hypothesize that distinct and uncharacterized classes of signaling and regulatory proteins bind directly to core telomeric proteins and modulate telomere homeostasis. Our long-term goal is to elucidate the mechanisms by which telomeric proteins and their associated factors regulate various signaling pathways at the telomeres. The goal of this project is to systematically identify novel regulators recruited to the telomeres by telomeric proteins such as TRF2, and to study how these targets may participate in telomere regulation. The specific aims of the proposal are: Specific Aim 1: To systematically identify new telomere regulators and signaling networks. Genome-wide approaches will be employed to identify new cellular targets of TRF2, and generate high-resolution maps of TRF2-centric signaling networks. Secondary screens are proposed to confirm and prioritize the targets identified. Specific Aim 2: To determine the function of the newly identified regulators. This aim will focus on new TRF2 targets PNUTS and ubiquitin E3 ligases, in their regulation of TRF2 function and telomere maintenance, and possible roles in extra-telomeric activities.